A giant magnetoresistance (GMR) element including a multilayer film including a ferromagnetic layer and a nonmagnetic layer and a tunneling magnetoresistance (TMR) element using an insulating layer (a tunnel barrier layer, a barrier layer) in a nonmagnetic layer are known. These have gained attention as elements for magnetic sensors, high-frequency components, magnetic heads, and nonvolatile random access memories (MRAMs).
An MRAM reads and writes data by using a characteristic in which an element resistance of a GMR element or a TMR element changes when magnetization directions of two ferromagnetic layers sandwiching an insulation layer change. As a writing method of the MRAM, a writing method (magnetization reversal) using a magnetic field generated by a current or a writing method (magnetization reversal) using a spin transfer torque (STT) generated by a current flowing in a lamination direction of a magnetoresistance effect element is known.
In the magnetization reversal of a magnetoresistance effect element using an STT, a current needs to flow in the lamination direction of the magnetoresistance effect element when writing data. There are cases in which a writing current may degrade the characteristics of the magnetoresistance effect element.
Therefore, in recent years, writing methods which do not need to allow a current to flow in the lamination direction of the magnetoresistance effect element have gained attention. One of these methods is a writing method using a spin-orbit torque (SOT) (for example, see I. M. Miron, K. Garello, G. Gaudin, P.-J. Zermatten, M. V. Costache, S. Auffret, S. Bandiera, B. Rodmacq, A. Schuhl, and P. Gambardella, Nature, 476, 189 (2011)). The SOT is caused by a spin current generated by a spin-orbit interaction or a Rashba effect at an interface between dissimilar materials. A current causing the SOT in the magnetoresistance effect element flows in a direction intersecting the lamination direction of the magnetoresistance effect element. That is, since a current does not need to flow in the lamination direction of the magnetoresistance effect element, improvement in durability of the magnetoresistance effect element can thus be expected.